Fuel cell technology potentially provides clean and efficient energy for stationary and traction applications. In order to be amenable to common usage, a fuel cell is best implemented in a form which provides reasonably high reaction efficiency near ambient temperatures, preferably below 100 degrees Celsius. However, the state-of-the-art of catalyst and membrane technology requires substantial working area between the electrodes to achieve commercially useful current at a reasonable potential at these temperatures. Current art commonly specifies large, flat electrodes to achieve the high surface area; however, this implementation requires precision-made plates, large rectangular seals, and complex reagent flow fields in order to function. These designs lead to a high-cost product with low reliability.
One known technique for improving the used surface area per unit volume of a fuel cell involves spirally winding the electrode assembly of the fuel cell. However, this technique does not include a mechanism to separate the fuel gas from the oxidizer, which is a necessary element for safe and efficient operation of the fuel cell. The technique presumes that the combustible fuel and oxidizer streams leading into the fuel cell are mixed prior to being introduced to a catalytic surface. Moreover, the technique does not afford a method for control over the fuel-oxidizer-inerts mixture, which changes dynamically throughout discharge.
One method used in the production of high surface area electrodes in commercially viable packages involves spirally winding the electrode elements around a core mandrel, which often also serves as one of the terminals. While this is a common and easily automated technique used in the commercial battery industry, the nature of fuel cells is such that active material immobilization (a presumption of wound electrodes) is not possible. Moreover, the typically low efficiency of the fuel cell reactions generates an additional requirement that the substantial quantity of waste heat due to polarization be removed.
Therefore, a spirally-wound fuel cell assembly which has high operational efficiency and occupies a relatively small volume of space is needed.